Method and apparatus for charging blast furnaces



METHOD AND APPARATUS FOR CHARGING BLAST FURNACES Filed Aug. 20, 1951 Feb. 9, 1954 H. w. CAMPBELL ETAL 4 Sheets-Sheet l INVENTORS He zvev C/QMPBELL Cam I? Jams 501v 57% a/Zfl K /fiemu HTI-oQ/vEYs 1954 H. w. CAMPBELL ET AL 2,668,623

METHOD AND APPARATUS FOR CHARGING BLAST FURNACES Filed Aug. 20, 1951 4 Sheets-Sheet. 2

INVENTORS HENRY W CAM/" 5541 x C431 .foH/vs o N METHOD AND APPARATUS FOR CHARGING BLAST FURNACES Filed Aug. 20, 1951 Feb. 9, 1954 H. w. CAMPBELL ETAL 4 Sheets-Sheet 3 Fig-4 INVENTORS Hf/VOYM CAMPBtZL a; C62! JOHNSON Feb. 9, 1954 v H. W. CAMPBELL ETAL METHOD AND APPARATUS FOR CHARGING BLAST FURNACES Filed Aug. 20, 1951 4 Shcets-Shee t 4 42 (a I 6 V fig-5 -m n 0-4 5 4/ M 2 I mgm 50-14 IN V EN TORS Haw)? y N 07/1/7054 4 7C Patented Feb. 9, 1954 "UNITED STATES ATE-NT OFFICE METHOD AND APPARATUS FOREHARGING BLAST FURNACES corporation of New York Application August 20, 1951, Serial'No. 242,618

17 Claims. -1

'fIhis invention relates to blast furnaces-and zparticular'ly -to -a method and apparatus for charging the furnace.

(One :method for charging a blast furnace, is tmdischarge aloadaof stock from a skip car-:into 'a smallrhopper,-the:bottom of which is. closed :off :by arbell :whichcantbe lowered to dischargethe ,stockintoai larger hopper which in", turn is closed :ofi'by. a larger bell. As soon asthe large hopper ;has -received a-halfround-of the stock, usually nconsisting of two-skip'car loads of coke, and zonecskipieachof ore and "stone, the large belljs opened and the stock is dropped into the furnace. -.Where1tw,o skip scars are used for hoistin vthe stock, one is hoisted to the top-of the furnace on :one track, while the empty car is lowered on theother track. Thus, the cars discharge ;.their;1oads%to one side'or the other of the center of thefurnacethere beinga receiving hopper or chutefor '"funneling'the stockinto the small hopper. This causes an off-center loading of :the small hopper, thus resulting in an uneven .--stock,charge ontorthe largebell, andarcorrei-sponding. uneven distribution of stock in the fur- :nace. Such unevendistribution is very unde- .sirable.

A methodheretofore used in an efiort'to eliminate-theirregularity of distribution is to rotate the small bell andhopper as a unit a'fixed' numberof degreeshafter the stock hasbeen dumped .into1it,.and before the'charge is droppe'd onto =thellarge :bell, The usual'practice has been to rotate-the hopper 60 for each dump of thesm-all bell :for'oneroundef charge, 120 for'the next, 189 forthe next, 240 for the next, 300,for the \next ande no movementfor the next'round. This distributes; the uneven loading of the stock around .the .furnace at 6 points, and the equipment as ea wholeis thus usually referred to as a 6 point distributor.

Anothermethcd has-been to utilizea single .sk ip car Which dumps its-load into the-center (oft-the small hopper thus attempting to, eliminate .ilhe, side .ieccentricity of loading. The materials {pouring out it of the skip car, .hcwever, tend to .,loa'd:the small hopper-higher-on one-side than on the other depending upon the nature of now of the different materials which constitute the stock. .The 6 point distributor, therefore, .iscus- Etomarily used with a single skip car in an. efiort .,to diminish.or. smooth out-the uneven distribu- -.tion.

730th. of the {foregoing methods do not provide asatistactory: even distribution but produce --i-n- ,gstead,..what might lee-termed a uniformlyirregu- ,larorlistribution, because. of the fact-that thexun- 2 even'loading of the stock on the small bell is distributed at'6 points in thefurnace.

iA-third'method of charging the furnace in- -cludesa-constructionby means of which the small bell and2hopper are-lifted as a unit from the'to-p of the furnace "and then "lowered to the stock house adjacent thebase of the furnace for fill- "At'the'loading point,-the bell and 'hopper ing and :hitveringithe beH and "hopper as a unit is so cumbersome and expensive that it is;-'sel dom used. tA'further objection is the 'fact'that whenever the hopper is transported to-thetop of thefurnace, it mustbe sealed so as to prevent undue 'escape of gas whenever the bell of the large hopper islowered for discharging t-he contentsthereof into-'thefurnace. "The problem mitting the hopper'to be :periodi-cally removed when empty and repositioned when loaded has also'been :a serious objection to the use of such method.

One 1131' :the causesof unequal -distribution is the difference in :the. physical characteristics of :the various *materialswithz'whichf the furnace is charged. "Such rdifierences cause thedifferent anaterials .to vary in .the .path taken by them as theyleave-ithe skip ".car and pass'through'the receiving hopper or funnel. Thus, for example,

ta skip car will emptytitstl'oad of -cokein-about four seconds, whereas "the time required I to {discharge one ,will'vary 'from approximately three :SECQDCIS 'tO- fourteen seconds. The moisture content in the ore is a factor?in=the*time required for discharging "it. Thus, :a wet,-sticky ore will cling :to the car until-vit-ri-s tipped't-o a certain angle, whereup0n :-the load slides 'quiokly and nearly straight down the side of the receiving A qpper. 0n the other :hand, a dry .stoney ore -.will zleavethe car-more gradually andwilhrequire :as high as 211.4 .seconds :to unload. Moreover, the dry crew-will swirl. around the :receiving ,=-hopper during the dumping operation. irregularities, itherefore, are repeated at each dumpinecperaticn.

'Such An object of :thmpresentinventionis to-retain the inherentwadvantage;rifkeepingthesmall hop- :per ;at-.the topxof the furnaceand of obtaining uniform distr"rbution of;-stock :within the 'furnace withoutlencountering any Qfzthe objections'here- 'tqferesset forth.

iBrlefinz-the:prescntainventioncontemplates -the 'ly shown) rotation of the small hopper, together with its associated bell, substantially a complete revolution in the shortest period of time required for dumping any of the different materials utilized for charging the furnace. The invention contemplates a continuous rotation of such hopper durin the dumping operation, and preferably an initiation of the rotation as the skip car approaches the top of the furnace. suitable time is permitted for accelerating the hopper and bringing it up to the desired speed by the time that the skip car is in position for dumping its load. The invention further preferably contemplates a stoppage of hopper rotation either after the skip car has been dumped, or after the small bell has been dumped, as desired.

Referring to the drawings, Fig. 1 is a vertical section of a furnace top and charging mechanism, to which our invention may be applied; Fig. 2 is a vertical section taken on a scale larger than that shown in Fig. 1, and illustrating the seal between the upper hopper and the body of the furnace; Fig. 3 is a vertical section taken on a scale larger than that in Fig. 2 and illustrating a driving mechanism for the upper or small .is shown a small bell and a large bell I2, arranged in series with one another.

The small bell is attached to the lower end of a tube I5, which is adapted to be raised and lowered by a hoisting mechanism (not shown) for raising and lowering the bell with respect to a small hopper 20. The large bell is attached to the lower end of a rod 2| which passes through the tube l5 and which is adapted to be raised and lowered by suitable hoisting mechanism (not complete- The large bell is thereby adapted to be raised and lowered with respect to a large 'hopper 25. Thus, the small bell normally holds the bottom of the hopper 20 closed, while the large bell holds the bottom of the hopper 25 closed.

Disposed above the hopper 20 is a receiving hopper or funnel 3|) into which the contents of a skip car, indicated by the broken lines 3|, may

-be dumped when the car reaches the top of an inclined trackway 32.

The present invention contemplates the rotation of the small hopper 20 and small bell H, at least substantially a complete revolution, for the shortest period of time required for dumping a carload of material into the receiving funnel. Accordingly, the hopper 20 is mounted for rotation with respect to the body of the furnace, and is shown as having a laterally extending circular flange 33 to which is attached a ring gear 34, which is adapted to mesh with a pinion 35 on a shaft 36. The shaft is journalled in a suitable housing 31 and is adapted to be driven -by a worm wheel 38 which meshes with the worm '39. The worm is fixed to a shaft 40 which is adapted to be driven by an electric motor 4|.

Thus, the hopper 20, and its associated bell H,

are rotated whenever the motor 4| is rotated.

The hopper 20 may be supported for rotation Thus,

upon spaced rollers 45, each of which is journalled in a bearing 46, the latter of which may be attached to the furnace body l0 by brackets 4'1. The rollers are adapted to engage an annular trackway 48 which is attached to a flange 50, the latter of which extends laterally from the upper end of a sleeve 5| and is in turn rigidly attached to the flange 33. Thus, the sleeve 5| rotates with the hopper and is disposed between the outer wall of the'furnace body, and an inner concentric wall 55. In this Way, the space between the walls 54 and 55 provides a receptacle 56 for holding water, whereas the bottom of the sleeve 5| terminates short of the bottom of the receptacle, whereby water may be introduced into the reservoir through a conduit 51 and withdrawn through a conduit 58, thus providing adequate circulation of water by means of which the receptacle 56 may be maintained full of water up to the level of the draw-oil conduit 58 in order to seal the rotating hopper against leakage of gas from the furnace body.

In the ordinary operation of a furnace, the skip car will deliver one or more loads of ore, coke and stone in accordance with a predetermined charging plan, but the time required for dumping each load will vary, as previously stated, from approximately 3 seconds to 14 seconds. The present invention, therefore, contemplates the initiation of a rotation of the hopper 20 so as to bring it up to speed as the car approaches the top of the furnace. The invention additionally contemplates a continuous rotation of the hopper during the dumping operation, and at a rate of one complete revolution for substantially the shortest period of time required to dump any car load. Thus, for the example given, the hopper would be rotated 20 revolutions per minute, whereby the material being dumped in the shortest period of time will be uniformly distributed entirely around the hopper regardless of the order in which the material is brought to the top of the furnace, and regardless of the nature or condition of the material at the time of delivery to the furnace. The phrase "uniformly distributed means that at the completion of each dumping operation, the material is substantially level in the rotating hopper.

The preferred method of operation is to rotate the hopper only during the dumping operation of the skip car, Wherefore, provision is made for closing the circuit to the motor 4| as the car approaches the top of the incline and sufficiently in advance of the commencement of the dumping operation to permit acceleration of the hopper to the desired speed of rotation. One method of accomplishing this is to provide a switch in circuit with the motor and to actuate the switch by a member which is connected to thedrum used for hoisting the skip car. A preferred manner of stopping the rotation of the motor at the completion of the dumping operation is to utilize a timer which is in circuit with the starting switch and motor, and which is set for stopping the motor in a predetermined number of seconds after the closing of the circuit. The timer is adjustable and can, therefore, be set to interrupt the motor circuit, as desired, by stopping the rotation of the hopper at the completion of the dumping operation. In practice the hopper may, if desired, be kept stationary for a sufiicient length of time between movements of the skip car to permit lowering of the bell I for discharging the contents of the hopper 20, or may, if desired, be kept rotating until the hopper 20 is woosgces rxiischarge'd :an'd the nbell if! .is returned to ":the

closed position.

'fie?schematiowiringrdiagram-zofifi igs 5'.-is illusrtrative for ::an iinstal-lation rutilizing r a single skip z-cargwherein the'imotord'l maybe supplied with ccurrenttzthrough lines L-ii and Lek-and may have, -in tits .circuit, ;a :;starting switch, indicated :at :a :rstoppin'g switch whichisiinclude'd .in itiimer, indicated in general at s5 The: starting :switchii's biasedl'to :open position iby a=1spring 162, whereas "the z stopping switch within the timer iis'lbiasedi to closed position. An ;:operating memherindieatedxattfiA may be? moved .in the direcction .irrdicatediby the: arrow- :eii byrotation of the hoisting cdrum for the skip 'car'in any suitable Way. Thus, .03? the switch 15:? *causes .a ifiow .o'ficurrentifrom'thezlineL i through con- -tactor e64, :iine 165, timer .1M, line =6,'m0tor":il, :li11e* 61:1an'd?b'ack to line .LZ. Closing'oi i the 'cirrcuit'ienergize'sa solenoid ti; through'lines' es and HLIthusDp'eratiIIg torholdi switch Bdclosed until ithe circuit is "opened by the 1 timer. Opening of .thevcircuit deenergizes the Psolenoidafit thus al- Zlowting 'arspring 62 tOilflOVe'thefiSWltCh'613 13011118 copeniposition. 'Inpracticethe-timer is adjusted storopen the circuit after'themaximum.timesrequired for any "dumping operation, wherefore the .':motor rotates continuously at a rate equal at least to substantially one revolution for the minismum time required .for any dumping operation. The opening of theroircuit may'be either at the endiof theperiod of'tim'e: required for the-iongest (limping-operation oruntil after the contents of the rotating hopper-have been dumped into'the large hopper.

Where two cars arexused for loading a furnace :then a rschematiowiring 'diagra'rnsuitable for opaerating a single motor is shown iniFig. i6 wherein aparts corresponding to those iofFig.-5-are desig nated by the same reference characters. -6,'h0wever, thereis' an additional starting switch (Gil, together with anadditional solenoid 8%. The :same timer can he used, hence, whenever the member SGEA .is actuated aduring the movement ofone-car'toward thetop of the iurnace, the

*circuit bearing the same reference characters: as '5 wouldvbe operated in the same manner for actuatingthe motor 4%. 0n; the other-hand, whenever the other car isnioving toward the topzofthe furnace-the member-Burk would .operate to close'the switched, whereupon the cur- :rent 'fiowatsuch-time would befrom-Iine L-B to contactor 82, 'switch' ii-ii line 83, timer 6 I, line :66, motor 1% l ,line 61. and back'to' lineL-Z. Eneregiz-ation-of the timer alsocompletes a cirou-it rthrough line M, solenoid 8 l and line 35 to i hold the switch =88 closed until the-timer operates to open the: motor circuit.

clan-advantage ofzthe present-invention-is the fact thata uniform distribution of the material I is attained. This isevidenced by the fact that greatly to the life of .the furnacelining, and

quality of iron produced. A further advantage 'isthat'the even distribution hasbeen an important factor in reducing the amount of line dust emanating :from the furnace. Thus, "for In Fig.

example, it ihas "been found "that a 'l'furnace opcrating in 'accordance'with this invention has shown a reduction of flue dustfrom about 200 pounds p'er ton of iron to about 5.0 :pounds :per ton so'f iron. Such reduction has resulted in higher efficiency of furnace operation.

We claim:

1. -."A :method of charging a blast furnace, *wherein imaterials'to befed into the-furnace "are delivered to the'top'ofthe furnace in skip carload riots and i are dumped .into a hopper which is-rcl-osed at 'the bottom by amovable bell, and 'wherein thetime required fordumping any skip 'carload varieswiththenature and physical conditions of the material, comprising rotating the hopper continuously from the time that the .maiterial'comm'ences-toleave*the car anduntil all ofathematerial is dumped'into the'hopper, said :rotation "being at suchspeed that the hopper makes substantially one revolution during'the time required for theefast-est dumping operation of :all'of the materials'to be fed into the furnace, whereby at the oompletion of eachdumping of= a skip car, the-material in the rotating'hopperis substantially level.

2.:A method of charging a blastiurnace with materialswhich are delivered to the-top of the furnace in-skipoarload lots, and are dumped into 'a'hopperwh-ich is closed at the bottom by a movable bell, wherein the "time required for complete removal of the contents of each car, varies 'from approximately 3 to approximately 14 seconds, comprising rotating-the hopper and :bell as a unit continuously "during the entire dumping operation of each skip carload, thespeed of rotationbeing--at-least-one revolution inapproximately three seconds.

3. A -method of charging a blast furnace wherein materials to be-rfed' into' the iurnaceare delivered to thetop'of itins'kip-carload lots and are *dumped into a hopper which is closed sat the bottom by a movable bell and wherein the time A required for dumping a-skip carload "varies with thenatureand physical condition of the -materia1; comprising initiating the rotation of the hopper and-bell asa unit as the car approaches the top of the furnace, said initiation occurring sufiiciently inad-vance of-theiarrival of thecar at the top K of the furnace :to' enable the hopper tocbe accelerated to'uniform speed -at thezcominenoement of the dumping operation, maintaining .a speed of rotation such that one complete urevolutionof the hopper is made for the iastest time inwhich. the dumping operation can beeperiormedwhereby at the completion of each dumpingof a skip car,.the material in the rotating hopperissubstantially level and then stopping .the rotation of the hopper within a predetermined period of time afterthe-initiation of the hopper rotation.

.4. .A method of charging .a blast furnace wherein materials to be .fed into the furnace are delivered-to the top of'it in skip ca'rload lots and aredumped into. a hopper which is closed at .the'bottom bya .movablebell, and Whereinthe time requiredrfor dumpinga skip carioad varies with-the nature andphysical-condition of the material, comprising initiating the rotation of i the 'hopperand bell as a unit as the carapproaches .thetop of the furnace, said initiation occurring sufficiently in advance of the arrival of the car at'the topof-the furnace to enable the hopper to be acceleratedto uniform speed at the commencementof the dumping operation, maintaining aspee'd of rotation such-that one comjplete revolution of the hopper is made fior'the fastest time inwhichthe dumping o'perationoa'n 'be performed, whereby at the completion of each dumping of a skip car, the material in the rotating hopper is substantially level and then stopping the rotation of the hopper after the car has been dumped.

5. A method of charging a blast furnace,

wherein materials to be fed into the furnace are delivered to the top of it in skip carload lots and are dumped into a hopper which is closed at the bottom by a movable bell, there being two cars for each furnace, and 50 arranged that an empty car is moving downwardly while a loaded car is 'moving upwardly, and wherein the time required 'for dumping a skip carload lot varies with the such speed that the hopper makes at least one revolution during the time required for the fastest dumping operation, initiating the rotation of the hopper sufiiciently far in advance of the arrival of any car at the top of the furnace that the hopper may be accelerated to a uniform rate of speed by the time that the dumping operation commences, whereby at the completion of each dumping of the skip car, the material in the rotating hopper is substantially level and stopping the rotation of the hopper after each car has been dumped.

6. A method of charging a blast furnace, wherein materials to be fed into the furnace are delivered to the top of it in skip carload lots and are dumped into a hopper which is closed at the bottom by a movable bell, there being two cars for each furnace, and so arranged that an empty car is moving downwardly while a loaded car is moving upwardly, and wherein the time required for dumping a skip carload lot varies with the nature and physical condition of the material, comprising rotating the hopper and its associated bell as a unit continuously during the entire dumping operation of each skip carload and at such speed that the hopper makes at least one revolution during the time required for the fastest dumping operation, whereby at the completion of each dumping of a skip car, the material in the rotating hopper is substantially level, initiating the rotation of the hopper sufficiently far in advance of the arrival of any car at the top of the furnace that the hopper may be accelerated to a uniform rate of speed by the time that the dumping operation commences, stopping the rotation of the hopper after each car has been dumped and before the other car delivers a load to the furnace, and lowering the bell to discharge the load in the hopper while the hopper is stationary.

'7. An apparatus for charging a blast furnace, comprising in combination, a furnace having a hopper and bell supported for rotation at the top thereof, a liquid seal between the hopper and the top, an electric motor connected to the hopper, a skip car, means for moving the skip car up an incline to deliver a load of material into the hopper, switch means in circuit with the motor for initiating the operation of it as the skip car approaches the top of the furnace, said switch means being actuated while the car is sumciently far from the top of the furnace to allow the motor to accelerate to uniform speed by the time that the car reaches the top of the furnace, said uniform speed being at least one "into the hopper, whereby at the completion of 8 each dumping of a skip car, the material in the rotating hopper is substantially level.

8. An apparatus for charging a blast furnace, wherein materials to be fed into the furnace are delivered to the top of it in skip carload lots, and wherein the cars are dumped into a hopper which is closed by a movable bell, comprising in combination, means for rotating the hopper and bell as a unit at a speed substantially equal to one revolution for the time required for the material in any skip carload to start flowing from the car into the hopper and until the entire contents are discharged into the hopper, whereby at the completion of each dumping of a skip car the material in the rotating hopper is substantially level, an electric motor for rotating the hopper, switch means in circuit with said motor, said switch means being operated sufiiciently in advance of the arrival of any car at the top of the furnace, that the hopper is accelerated to a uniform speed before the dumping operation starts, a second switch in circuit with said motor, timer means in circuit with said motor, and switch means responsive to the operation of said timer means for disconnecting the motor circuit within a predetermined period of time after the motor has been started.

9. In combination, a blast furnace, a material receiving hopper positioned at the top thereof, a movable bell closing the hopper, an electric motor for rotating the hopper, a source of current supply in circuit with the motor, a pair of skip cars each having an inclined trackway leading from the bottom to the top of the furnace, switch means in circuit with said motor, and adapted to be actuated as each car is moved upwardly along the trackway for connecting the motor with the source of supply, a timer, and means responsive to the operation of the timer for disconnecting the motor from its source of current supply, said last-mentioned means being actuated after one car has been dumped but before the other car has been raised to a point where the motor circuit is closed, said timer operating to effect rotation of the hopper continuously during the dumping of each skip load and at sufiicient speed that at the completion of each dumping of a skip car, the material in the r0- tating hopper is substantially level.

10. A method of charging a blast furnace, wherein materials to be fed into the furnace are delivered to the top of it in skip carload lots and are dumped into a hopper which is closed at the bottom by a movable bell, and wherein the time required for dumping any skip carload varies with the nature and physical conditions of the material, comprising, rotating the hopper at a speed of substantially one revolution during the time required for the fastest dumping operation of all of the materials to be fed into the furnace, whereby at the completion of each dumping of the skip car the material in the rotating hopper is substantially level, maintaining the rotation during the time required for dumping a skip load, and holding the hopper stationary while the movable bell is being lowered for emptying the contents of the hopper.

11. A method of charging a blast furnace wherein materials to be fed into the furnace are delivered to the top of it in skip carload lots and. are dumped into a hopper which is closed at the bottom by a movable bell, there being two cars for each furnace and so arranged that an empty car is moving downwardly while a loaded car is moving upwardly, comprising, rotating the hopper and its associated bell as a unit continuously during the entire dumping operation and at such speed that the hopper makes at least one revolution during the time required for th fastest dumping operation, whereby at the completion of each dumping of a skip car, the material in the rotating hopper is substantially level, initiating the rotation of the hopper sufficiently far in advance of the arrival of any car at the top of the furnace that the hopper may be accelerated to a uniform rate of speed by the time that the dumping operation commences, maintaining the rotation of the hopper during the dumping of each skip car, and then stopping the rotation until the other loaded car arrives at a predetermined point adjacent the top of the furnace.

12. A method of charging a blast furnace wherein materials to be fed into the furnace are delivered to the top of the furnace in skipload portions and are dumped into a hopper which is closed at the bottom by upward movement of a bell, which comprises rotating the hopper and associated bell continuously during the entire operation of discharging each skipload into the hopper, the rotation being at a rate sufiiciently rapid to make at least one complete revolution during the dumping of each skipload, and to effect substantially level distribution of the material in the hopper.

13. In the method of charging a blast furnace closed at the top by a relatively large and a relatively small bell and hopper type of closure, the small hopper being disposed above the large hopper, in which method materials to be fed into the furnace are delivered to the top of the furnace in skipload portions, each such portion being dumped into the upper hopper from which it is separately discharged into the lower hopper by lowering the small bell, thereby progressively building up in the lower hopper a charge of materials for ultimate discharge into the blast furnace upon lowering the large bell, the improvements which consist in rotating the upper hopper and associated small bell continuously during the entire operation of discharging each skipload of material into the upper hopper at a rate of rotation sufliciently rapid to eifect substantially at least one complete revolution during the entire dumping operation and to effect substantially level distribution of the material in said upper hopper, and successively delivering such substantially level portions of material to the lower hopper, whereby the latter is provided with a charge, which is substantially level.

14. A blast furnace having in combination, an annular liquid reservoir at the top thereof, a skip car for charging the furnace, a charge receiving hopper mounted for rotation on the furnace and having a cylindrical sleeve extending substantially the length of the hopper and disposed within the reservoir and terminating short of the bottom thereof, said sleeve cooperating with the walls of the reservoir to provile a, tortuous path for the flow of liquid out of the reservoir incident to the pressure which may be exerted upon the liquid by gas tending to escape from the furnace, and means for rotating said hopper at least one complete revolution during a charge receiving interval, whereby at the completion of each dumping of the skip car, the material in the rotating hopper is substantially level.

15. In combination, a blast furnace, a skip car therefor, a charge-receiving hopper mounted for rotation at the top of the furnace, a bell operable to close the hopper, an electric motor for rotating the hopper and means for connecting the motor to the hopper to effect at least one revolution of the hopper during the charging operation, whereby at the completion of each dumping of a skip car, the material in the rotating hopper is substantially level.

16. In combination, a blast furnace having a liquid reservoir open to the atmosphere at the top thereof, a skip car therefor, a hopper rotatablymounted at the top of the furnace, a bell movable upwardly for closing said hopper, said hopper having a smooth-walled interior, and having a sleeve depending therefrom into the reservoir but terminating short of the bottom thereof, and providing a partition, one side of which is adapted to be in communication with the interior of the furnace and the other side of which is adapted to be in communication with the atmosphere, whereby gas escaping from the furnace is forced to flow in a tortuous path downwardly on one side of the partition, and then upwardly on the other side of the partition, and means for rotating said hopper continuously and at least one revolution while material for charging the furnace is being dumped into it, whereby at the completion of each dumping of the skip car, the material in the rotating hopper is substantially level.

17. In combination, a blast furnace, a skip car therefor, said furnace having a, stationary hopper at the top thereof, a first bell providing a bottom closure for said stationary hopper, a hopper rotatably mounted on and above said stationary hopper, a second bell providing a bottom closure for the upper hopper, said upper hopper being adapted to receive a load of charging material while the second bell is in closed position and to discharge its contents into the stationary hopper upon lowering of the second bell while the bell of the stationary hopper is in closed position, means for rotating said upper hopper and said second bell continuously while said upper hopper is receiving a, load of charging material and at a rate equal to at least one complete revolution during the dumping operation, whereby at the completion of each dumping of the skip car, the material in the rotating hopper is substantially level, and a seal disposed between the upper hopper and the stationary hopper to prevent the escape of gas from the latter during the time in which the bell of the stationary hopper is lowered for discharging the contents of the latter into y the furnace.

HENRY W. CAMPBELL. CARL P. JOHNSON. 

